Thin film transistor and manufacturing method thereof

ABSTRACT

The present disclosure provides a manufacturing method of a thin film transistor, including: selecting a substrate, and forming a bottom gate, a gate insulating layer and a source-drain above the selected substrate, wherein the bottom gate and the source-drain adopts a conductive metal oxide with an adjustable work function as a metal conducting electrode; rinsing and drying the source-drain of the selected substrate, and ozone cleaning dried source-drain for a predetermined time under a predetermined illumination condition, bombarding the source-drain with oxygen plasma for a period of time, forming an active layer made of a carbon material over the source-drain; forming a passivation layer over the active layer. The implementation of the disclosure can reduce the contact resistance and improve the performance of the carbon-based thin film transistor device by adjusting the work function of the contact surface between the conductive metal and the active layer.

RELATED APPLICATIONS

The present application is a National Phase of International ApplicationNumber PCT/CN2017/113533, filed Nov. 29, 2017, and claims the priorityof China Application CN 201711175832.7, filed Nov. 22, 2017.

FIELD OF THE DISCLOSURE

The present disclosure relates to a thin film transistor technologyfield, and more particularly to a thin film transistor and amanufacturing method thereof.

BACKGROUND OF THE DISCLOSURE

The currently used amorphous silicon thin film transistors, IGZO (indiumgallium zinc oxide) thin film transistors and the like are sensitive tolight, due to the electrical properties of light drift and changeoccurs, so need to cover the active layer with opaque metal layer in thepreparation process to reduce the impact of light, making the displaydevice aperture ratio greatly reduced.

In view of carbon nanotubes and graphene and other carbon materials inthe structure of carbon atoms were presented as carbon atoms to sp2hybrid hexagonal ring structure of lamellar structure, has excellentelectrical properties, mechanical properties and chemical stability, canbe applied to high-frequency devices to improve the frequency responseof the device range, can also replace the traditional silicon-basedsemiconductor devices, prepared into high mobility, transparent,flexible curly thin film transistor. Compared with traditionalsilicon-based semiconductors and other III-V series semiconductors,carbon materials such as carbon nanotubes and graphene have obviousadvantages in the application of flexible transparent thin filmtransistors because of their advantages of high mobility, high opticaltransparency, long-term electrical stability and good mechanical bendingproperties.

However, in the production of thin film transistors, carbon materialssuch as carbon nanotubes and graphene are affected by factors such aspreparation method, dispersion solvent, semiconductor purity, and filmformation method, so that the work function of the active layer formedof carbon materials such as carbon nanotubes and graphene fluctuatebetween 4.2 eV and 5.2 eV. As we all know, the active layer is matchedwith the work function of the conductive metal. Reducing the contactresistance to form the ohmic contact is a guarantee for the excellentperformance of the transistor device. However, the contact between theactive layer formed by the carbon materials such as carbon nanotubes andgraphene and the metal electrode is not perfect ohmic contact. Forexample, conductive metal such as metal titanium Ti, metal palladium Pd,metal gold Au and metal platinum Pt are brought into contact with thecarbon nanotubes. Their work functions are close to those of the carbonnanotubes. Even though the contact resistance between the metal platinumPt and the carbon nanotubes is the smallest, the potential barrier stillexists. Therefore, using the same adjustable work function conductivemetal oxide (work function between 4.0 eV˜6.1 eV) for the work functionmatching is of great significance.

SUMMARY OF THE DISCLOSURE

The technical problem to be solved by the embodiments of the presentdisclosure is to provide a thin film transistor and a manufacturingmethod thereof, which can improve the performance of a carbon-based thinfilm transistor device by adjusting the work function of the contactsurface between the conductive metal and the active layer, reducing thecontact resistance.

In order to solve the above technical problem, the embodiments of thepresent disclosure provide a manufacturing method of a thin filmtransistor, wherein the method includes the following steps:

step S11, selecting a substrate, and forming a bottom gate, a gateinsulating layer and a source-drain from bottom to top in sequence abovethe selected substrate, wherein the source-drain adopts a conductivemetal oxide with an adjustable work function as a metal conductingelectrode;step S12, rinsing and drying the source-drain of the selected substrate,performing ozone cleaning to the dried source-drain for a predeterminedtime under a predetermined illumination condition, and bombarding thesource-drain after the ozone cleaning with oxygen plasma for a period oftime, and further forming an active layer made of a carbon material overthe source-drain after the oxygen plasma bombardment; andstep S13, forming a passivation layer over the active layer after thepreparation of the active layer is completed.

Wherein the step S11 specifically includes:

when a substrate made of a silicide is selected, depositing a layer ofthe conductive metal oxide having a thickness of first threshold on thesubstrate made of the selected silicide by radio frequency magnetronsputtering as the bottom gate, and using plasma enhanced chemical vapordeposition to deposit a layer of silicon dioxide having a thickness ofsecond threshold as the gate insulating layer;after the preparation of the gate insulating layer above the substratemade of the selected silicide is completed, depositing a layer of theconductive metal oxide having a thickness of third threshold bymagnetron sputtering as the source-drain, then preparing a source-drainpattern by coating photoresist, exposing, etching and removingphotoresist.

Wherein the step S12 specifically includes:

soaking and flushing the source-drain of the substrate made by theselected silicide with acetone, methanol and isopropanol; drying therinsed source-drain with a certain concentration of nitrogen; ozonecleaning the dried source-drain for 60 seconds under ultraviolet light;bombarding the source-drain after the ozone cleaning by oxygen plasmafor 60 seconds, before the active layer prepared from semiconductorcarbon nanotubes or silicon carbide is formed into a film;soaking the source-drain after the oxygen plasma bombardment into asemiconductor carbon nanotube solution or the silicon carbide solution,so that a layer of thin film deposited thereon is taken out and baked ata certain temperature to obtain a carbon nanotube network-like thin filmor a silicon carbide network-like thin film, then coating thephotoresist on the carbon nanotube network-like thin film or the siliconcarbide network-like thin film, and etching remaining portions of thecarbon nanotube network-like thin film or the silicon carbidenetwork-like thin film except fora channel portion of the transistorwith oxygen ions, continuing to remove the photoresist above the channelportion of the transistor in the carbon nanotube network-like thin filmor the silicon carbide network-like thin film to prepare a carbonnanotube channel or a silicon carbide channel film, so that an activelayer prepared from semiconductor carbon nanotubes or silicon carbide isobtained.

Wherein the step S13 specifically includes;

covering a certain thickness of silicon dioxide over the active layermade of semiconductor carbon nanotubes or silicon carbide by a chemicalvapor deposition method as a passivation layer, after the preparation ofthe active layer made of semiconductor carbon nanotubes or siliconcarbide is completed.

Wherein the selected substrate is a transparent substrate made of quartzor glass, and a transparent bottom gate, a transparent gate insulatinglayer, a transparent source-drain, a transparent active layer and atransparent passivation layer are formed above the correspondingsubstrate; wherein

the transparent gate insulating layer and the transparent passivationlayer are both made of a transparent insulating material includingsilicon dioxide, graphene oxide, silicon nitride, aluminum oxide and anorganic transparent insulating material;

the transparent bottom gate and the transparent source-drain are made ofa transparent conductive metal oxide with an adjustable work function asa metal conducting electrode, and the transparent conductive metal oxideincludes indium tin oxide, aluminum zinc oxide, tin oxide fluoride,gallium zinc oxide and zinc tin oxide;the transparent active layer is made of semiconductor carbon nanotube orsilicon carbide.

Wherein the method further includes;

depositing a layer of the transparent conductive metal oxide having athickness of seventh threshold as a transparent top gate by RF magnetronsputtering.

Correspondingly, an embodiment of the present disclosure furtherprovides another manufacturing method of a thin film transistor, whereinthe method includes the following steps:

step S21, selecting a substrate, and forming a bottom gate, a gateinsulating layer and a source-drain from bottom to top in sequence abovethe selected substrate, wherein the source-drain adopts a conductivemetal oxide with an adjustable work function as a metal conductingelectrode;step S22, rinsing and drying the source-drain of the selected substrate,performing ozone cleaning to the dried source-drain for a predeterminedtime under a predetermined illumination condition, and bombarding thesource-drain after the ozone cleaning with oxygen plasma for a period oftime, and further forming an active layer made of a carbon material overthe source-drain after the oxygen plasma bombardment;step S23, forming a passivation layer over the active layer after thepreparation of the active layer is completed.

Wherein the step S21 specifically includes:

placing a substrate made of a selected plastic in acetone andisopropanol, ultrasonic cleaning and then drying with nitrogen, when thesubstrate made of the plastic is selected;

forming a patterned photoresist on the selected plastic substrate by UVlithography and a conductive metal oxide with a thickness of fourththreshold deposited as the bottom gate by RF magnetron sputtering;patterning the bottom gate by de-photoresist, and then depositing anon-transparent insulating material with a thickness of fifth thresholdas the gate insulating layer by atomic force deposition technique; andpatterning the gate insulating layer through ultraviolet lithography andphosphoric acid wet-etching technology;depositing a conductive metal oxide with a thickness of sixth thresholdas the source-drain by magnetron sputtering, after the preparation ofthe gate insulating layer above the substrate made of the selectedplastic is completed; wet-etching an exposing indium tin oxide withphosphoric acid, after the photoresist is coated and the photoresist onthe coating is patterned by UV lithography; and preparing a source-drainpattern by removing the photoresist of the unexposed conductive metaloxide.

Wherein the step S22 specifically includes:

soaking and washing the source-drain of the substrate made of selectedplastic with acetone, methanol and isopropanol; drying the washedsource-drain with a nitrogen gas of a certain concentration; and ozonecleaning the dried source-drain for 60 seconds under ultraviolet light,before the active layer prepared from graphene is film-formed,bombarding the source-drain after the ozone cleaning with oxygen plasmafor 60 seconds;transforming graphene grown on a copper foil by polymethylmethacrylateonto the source-drain after the oxygen plasma bombardment to form a thinfilm, then coating the photoresist on the thin film formed by grapheneand etching remaining portions of the thin film formed by grapheneexcept for a channel portion of the transistor with oxygen ions,continuing to remove the photoresist above the channel portion of thetransistor in the thin film formed by graphene, so that an active layerprepared from graphene was obtained.

Wherein the step S23 specifically includes:

covering a certain thickness of silicon dioxide by a chemical vapordeposition method on the active layer made of graphene as a passivationlayer, after the preparation of the active layer made of graphene iscompleted.

Wherein the selected substrate is a transparent substrate made oftransparent plastic, and a transparent bottom gate, a transparent gateinsulating layer, a transparent source-drain, a transparent active layerand a transparent passivation layer are formed above the correspondingsubstrate; wherein,

the transparent gate insulating layer and the transparent passivationlayer are both made of a transparent insulating material includingsilicon dioxide, graphene oxide, silicon nitride, aluminum oxide and anorganic transparent insulating material;

the transparent bottom gate and the transparent source-drain are made ofa transparent conductive metal oxide with an adjustable work function asa metal conducting electrode, and the transparent conductive metal oxideincludes indium tin oxide, aluminum zinc oxide, tin oxide fluoride,gallium zinc oxide and zinc tin oxide;the transparent active layer is made of graphene.

Wherein the method further includes;

depositing a transparent conductive metal oxide with a thickness ofseventh threshold on the transparent passivation layer as a transparenttop gate by RF magnetron sputtering.

Correspondingly, an embodiment of the present disclosure furtherprovides a manufacturing method of a thin film transistor, wherein themethod includes the following steps:

step S31, selecting a substrate, and forming a source-drain on theselected substrate; wherein the source-drain adopts a conductive metaloxide with an adjustable work function as a metal conducting electrode;

step S32, rinsing and drying the source-drain of the selected substrate,performing ozone cleaning to the dried source-drain for a predeterminedtime under a predetermined illumination condition, and bombarding thesource-drain after the ozone cleaning with oxygen plasma for a period oftime, and further forming an active layer made of a carbon material overthe source-drain after the oxygen plasma bombardment; andstep 33, sequentially forming a passivation layer and a top gate frombottom to top on the active layer, after the active layer is prepared.

Wherein the step S31 specifically includes:

when a substrate made of silicide is selected, depositing a layer of theconductive metal oxide having a thickness of third threshold on thesubstrate made of silicide by magnetron sputtering as the source-drain,then preparing a source-drain pattern by coating photoresist, exposing,etching and removing photoresist.

Wherein the step S32 specifically includes:

soaking and flushing the source-drain of the substrate made by theselected silicide with acetone, methanol and isopropanol; drying therinsed source-drain with a certain concentration of nitrogen; ozonecleaning the dried source-drain for 60 seconds under ultraviolet light;bombarding the source-drain after the ozone cleaning by oxygen plasmafor 60 seconds, before the active layer prepared from semiconductorcarbon nanotubes or silicon carbide is formed into a film;soaking the source-drain after the oxygen plasma bombardment into asemiconductor carbon nanotube solution or the silicon carbide solution,so that a layer of thin film deposited thereon is taken out and baked ata certain temperature to obtain a carbon nanotube network-like thin filmor a silicon carbide network-like thin film, then coating thephotoresist on the carbon nanotube network-like thin film or the siliconcarbide network-like thin film, and etching remaining portions of thecarbon nanotube network-like thin film or the silicon carbidenetwork-like thin film except for a channel portion of the transistorwith oxygen ions, continuing to remove the photoresist above the channelportion of the transistor in the carbon nanotube network-like thin filmor the silicon carbide network-like thin film to prepare a carbonnanotube channel or a silicon carbide channel film, so that an activelayer prepared from semiconductor carbon nanotubes or silicon carbide isobtained.

Wherein the step S33 specifically includes:

after the preparation of the active layer made of semiconductor carbonnanotubes or silicon carbide is completed, covering a layer of silicondioxide with a certain thickness over the active layer made ofsemiconductor carbon nanotubes or silicon carbide by a chemical vapordeposition method as a passivation layer, and using a radio frequencymagnetron sputtering method to deposit a conductive metal oxide with athickness of seventh threshold on the passivation layer as the top gate.

Wherein the selected substrate is a transparent substrate made of quartzor glass, and a transparent source-drain, a transparent active layer, atransparent passivation layer and a transparent top gate are formedabove the corresponding substrate; wherein

the transparent passivation layer is made of transparent insulatingmaterial, the transparent insulating material includes silicon dioxide,graphene oxide, silicon nitride, aluminum oxide and organic transparentinsulating material;

the transparent source-drain adopts a transparent conductive metal oxidewith an adjustable work function as a metal conducting electrode;

the transparent active layer is made of semiconductor carbon nanotube orsilicon carbide;

the transparent top gate adopts a transparent conducting metal oxidewith adjustable or non-adjustable work function as a metal conductingelectrode;

the transparent conductive metal oxide includes indium tin oxide,aluminum zinc oxide, tin oxide, gallium zinc oxide, and zinc tin oxide.

Wherein the step S31 further includes:

when a substrate made of plastic is selected, depositing a layer of theconductive metal oxide having a thickness of third threshold on thesubstrate made of plastic by magnetron sputtering as the source-drain,then preparing a source-drain pattern by coating photoresist, exposing,etching and removing photoresist.

Wherein the step S32 further includes;

soaking and washing the source-drain of the substrate made of selectedplastic with acetone, methanol and isopropanol; drying the washedsource-drain with a nitrogen gas of a certain concentration; and ozonecleaning the dried source-drain for 60 seconds under ultraviolet light;before the active layer prepared from graphene is film-formed,bombarding the source-drain after the ozone cleaning with oxygen plasmafor 60 seconds;transforming graphene grown on a copper foil by polymethylmethacrylateonto the source-drain after the oxygen plasma bombardment to form a thinfilm, then coating the photoresist on the thin film formed by grapheneand etching remaining portions of the thin film formed by grapheneexcept for a channel portion of the transistor with oxygen ions,continuing to remove the photoresist above the channel portion of thetransistor in the thin film formed by graphene, so that an active layerprepared from graphene was obtained.

Wherein the step S33 further includes:

after the preparation of the active layer made of graphene is completed,covering a layer of silicon dioxide with a certain thickness on theactive layer made of graphene by a chemical vapor deposition method as apassivation layer, and using a radio frequency magnetron sputteringmethod to deposit a conductive metal oxide with a thickness of sevenththreshold on the passivation layer as a top gate.

Wherein the selected substrate is a transparent substrate made oftransparent plastic, and a transparent source-drain, a transparentactive layer, a transparent passivation layer and a transparent top gateare formed above the corresponding substrate;

the transparent passivation layer is made of transparent insulatingmaterial, the transparent insulating material includes silicon dioxide,graphene oxide, silicon nitride, aluminum oxide and organic transparentinsulating material;

the transparent source-drain adopts a transparent conductive metal oxidewith an adjustable work function as a metal conducting electrode;

the transparent active layer is made of graphene;

the transparent top gate adopts a transparent conducting metal oxidewith adjustable or non-adjustable work function as a metal conductingelectrode;

the transparent conductive metal oxide includes indium tin oxide,aluminum zinc oxide, tin oxide, gallium zinc oxide, and zinc tin oxide.

In the present disclosure, two steps of ozone cleaning and oxygen plasmatreatment on the conductive layer of the metal oxide (i.e., thesource-drain) are added in the mature process and process of theexisting amorphous silicon thin film transistor, improving the surfacework function of the conductive metal oxide to make good ohmic contactwith the active layer of the carbon material so as to improve theperformance of the carbon-based thin film transistor device, moreover,the present disclosure can be applied to the preparation of anon-transparent carbon-based material thin film transistor and also tothe preparation of a fully transparent carbon-based material thin filmtransistor.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentdisclosure or in the prior art more clearly, the following brieflyintroduces the accompanying drawings required for describing theembodiments or the prior art. Apparently, the accompanying drawings inthe following description show merely some embodiments of the presentdisclosure. For those skilled in the art, other drawings based on thesedrawings are still within the scope of the present disclosure withoutany creative efforts.

FIG. 1 is a flow chart of a manufacturing method of a thin filmtransistor according to Embodiment 1 of the present disclosure.

FIG. 2 is a flow chart of another manufacturing method of a thin filmtransistor according to Embodiment 2 of the present disclosure.

FIG. 3 is a flow chart of the other manufacturing method of a thin filmtransistor according to Embodiment 3 of the present disclosure.

FIG. 4 is a flow chart of the other manufacturing method of a thin filmtransistor according to Embodiment 4 of the present disclosure.

FIG. 5 is a flow chart of the other manufacturing method of a thin filmtransistor according to Embodiment 5 of the present disclosure.

FIG. 6 is a flow chart of the other manufacturing method of a thin filmtransistor according to Embodiment 6 of the present disclosure.

FIG. 7 is a partial cross-sectional view of a thin film transistoraccording to Embodiment 8 of the present disclosure.

FIG. 8 is a partial cross-sectional view of another thin film transistoraccording to Embodiment 10 of the present disclosure.

FIG. 9 is a partial cross-sectional view of the other thin filmtransistor according to Embodiment 12 of the present disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred embodiments of the present disclosure are described belowwith reference to the accompanying drawings.

In order to make the objectives, technical solutions and advantages ofthe present disclosure clearer, the present disclosure will be furtherdescribed in detail with reference to the accompanying drawings.

As shown in FIG. 1, FIG. 1 is a flow chart of a manufacturing method ofa thin film transistor according to Embodiment 1 of the presentdisclosure. The method shows a method for preparing a non-fullytransparent bottom gate structure carbon-based material thin filmtransistor, which includes the following steps:

step S101, selecting a substrate, and forming a bottom gate, a gateinsulating layer and a source-drain from bottom to top in sequence abovethe selected substrate, wherein the source-drain adopts a conductivemetal oxide with an adjustable work function as a metal conductingelectrode;step S102, rinsing and drying the source-drain of the selectedsubstrate, performing ozone cleaning to the dried source-drain for apredetermined time under a predetermined illumination condition, andbombarding the source-drain after the ozone cleaning with oxygen plasmafor a period of time, and further forming an active layer made of acarbon material over the source-drain after the oxygen plasmabombardment;step S103, forming a passivation layer over the active layer after thepreparation of the active layer is completed.

The specific process is that in step S101, the selected substrate ismade of non-transparent material; the gate insulating layer is made of anon-transparent insulating material and is processed through a plasmaenhanced chemical vapor deposition method, an atomic force depositiontechnique, or other techniques. The bottom gate using conductive metaloxide or transparent conductive metal oxide as the metal conductiveelectrode and is processed through RF magnetron sputtering process. Thesource-drain using the adjustable work function conductive metal oxideor transparent conductive metal oxide as the metal conductive electrodeand is processed through magnetron sputtering process.

According to the different substrate materials, the bottom gate, thegate insulating layer and the source-drain prepared by the above methodalso have different preparation methods as follows:

in one embodiment, a silicide substrate is first selected and a 100 nmconductive metal oxide or a transparent conductive metal oxide isdeposited as a bottom gate on the silicide substrate by radio-frequencymagnetron sputtering. Secondly, a 400 nm non-transparent insulatingmaterial is deposited by plasma enhanced chemical vapor deposition(using silane and oxygen as raw material gases) as a gate insulatinglayer. Then, a magnetron sputtering method is used to deposit a 100 nmconductive metal oxide or a transparent conductive metal oxide with anadjustable work function as a source-drain.

In another embodiment, the plastic substrate is first selected, theselected plastic substrate is placed in acetone and isopropanol, cleanedwith ultrasonic and then blown dry with nitrogen. A patternedphotoresist is formed on the selected plastic substrate by UVlithography, and a conductive metal oxide or a transparent conductivemetal oxide with a thickness of 200 nm is deposited as a bottom gate byRF magnetron sputtering. The bottom gate is patterned by de-photoresist,then a 50 nm non-transparent insulating material is deposited as thegate insulating layer by the atomic force deposition technique, and thegate insulating layer is patterned by UV lithography and phosphoric acidwet-etching. A magnetron sputtering method is used to deposit a 100 nmconductive metal oxide or a transparent conductive metal oxide with anadjustable work function as a source-drain.

In step S102, the source-drain of the selected substrate are washed andrinsed with acetone, methanol and isopropanol, and the washedsource-drain are purged with nitrogen at a certain concentration (forexample, the concentration ratio is higher than 70%). Further, the driedsource-drain was subjected to ozone cleaning for 60 seconds underultraviolet light. Before the active layer was formed, the source-drainafter the ozone cleaning were bombarded with oxygen plasma for 60seconds. It should be noted that ozone cleaning and oxygen plasmatreatment include oxygen plasma bath and injection. Oxygen plasmatreatment can clean the organic impurities on the surface of theconductive metal oxide at the source-drain and at the same time increasethe oxygen content at the surface of the conductive metal oxide at thesource-drain and enhance the surface polarization so as to regulate thework function of the surface of the conductive metal oxide.

Wherein, the active layer is made of a carbon material, which includesthe semiconducting carbon nanotubes, the graphene and the siliconcarbide, and the specific method for preparing the active layer is asfollows:

(1) when the semiconductor carbon nanotube or silicon carbide is used toprepare the active layer, immersing the source-drain after the oxygenplasma bombardment into a semiconductor carbon nanotube solution or thesilicon carbide solution. So that a layer of thin film deposited thereonis taken out and baked at a certain temperature (for example, 150° C.for 30 minutes) to obtain a carbon nanotube network-like thin film or asilicon carbide network-like thin film. Then coating the photoresist onthe carbon nanotube network-like thin film or the silicon carbidenetwork-like thin film, and etching the remaining portions of the carbonnanotube network-like thin film or the silicon carbide network-like thinfilm except for the channel portion of the transistor with oxygen ions.Continuing to remove the carbon nanotube network-like film or siliconcarbide network-like film in the channel above the transistor part ofthe photoresist. Preparing a channel of the carbon nanotube or a channelof the silicon carbide to obtain an active layer prepared fromsemiconductor carbon nanotubes or silicon carbide (the active layer maybe adjusted to be transparent or non-transparent according to aprocess);(2) when the active layer is prepared by using graphene, transferringthe graphene grown on the copper foil onto the source-drain after oxygenplasma bombardment by polymethylmethacrylate transfer technology to forma thin film, then, applying photoresist over the thin film formed ofgraphene and etching the rest of the thin film formed by graphene withoxygen ions except for the channel portion of the transistor. Continuingto remove the photoresist layer above the channel portion of thetransistor in the thin film formed by graphene to obtain an active layermade of graphene. The active layer can be adjusted to be transparent ornon-transparent according to a process.

In step S103, above the active layer made of one of the semiconductingcarbon nanotubes, silicon carbide and graphene, a layer of silicondioxide with a certain thickness (for example, 500 nm) is covered by achemical vapor deposition method as a passivation layer.

As shown in FIG. 2, a manufacturing method of a thin film transistoraccording to Embodiment 2 of the present disclosure is shown. The methodshows a method for preparing a fully transparent bottom gate structurecarbon-based material thin film transistor. The method includes thefollowing steps:

step S201, selecting a substrate made of a transparent material andforming a transparent bottom gate, a transparent gate insulating layerand a transparent source-drain sequentially from bottom to top over theselected substrate; wherein, the transparent source-drain adopts atransparent conductive metal oxide with an adjustable work function as ametal conducting electrode;step S202, rinsing and drying the transparent source-drain of theselected substrate, and subjecting the dried transparent source-drain toa predetermined time of ozone cleaning under predetermined lightingconditions, then bombarding the transparent source-drain of the ozonecleaning with oxygen plasma for a period of time, further forming atransparent active layer made of a carbon material over the transparentsource-drain after the oxygen plasma bombardment;step S203, forming a transparent passivation layer over the transparentactive layer, after the preparation of the transparent active layer iscompleted.

The specific process is that, in step S201, the transparent material ofthe substrate includes quartz, glass and transparent plastic; the bottomgate also adopts the transparent conductive metal oxide with the samework function as the transparent source-drain as the metal conductingelectrode and the transparent conducting metal oxide includes indium tinoxide, aluminum zinc oxide, tin oxide fluoride, gallium zinc oxide andzinc tin oxide. The transparent gate insulating layer is made oftransparent insulating material, and the transparent insulating materialincludes silicon dioxide, graphene oxide, silicon nitride, aluminumoxide and organic transparent insulating material.

The substrate with different materials, the corresponding manufacturingmethod of the transparent bottom gate, the transparent gate insulatinglayer and the transparent source-drain formed from bottom to top insequence are different as follows:

in one embodiment, when a substrate made of quartz or glass is selected,using radio frequency magnetron sputtering on the selected quartz orglass substrate to deposit a layer of indium tin oxide having athickness of the first threshold (e.g. 100 nm) as a transparent bottomgate, and using plasma enhanced chemical vapor deposition (using silaneand oxygen as raw material gases) to deposit a layer of silicon dioxidewith the second threshold (e.g. 400 nm) in thickness as a transparentgate insulating layer;after the preparation of the transparent gate insulating layer above thesubstrate made of selected quartz or glass is completed, depositing alayer of indium tin oxide with a thickness of the third threshold (e.g.500 nm) as a transparent source-drain by magnetron sputtering, andpreparing transparent source-drain patterns by coating photoresist,exposing, etching and removing photoresist.

In another embodiment, when a substrate made of transparent plasticmaterial is selected, placing a substrate made of the selectedtransparent plastic material in acetone and isopropyl alcohol andultrasonically cleaning and then blown drying with nitrogen gas;

a patterned photoresist is formed by UV lithography over a substrate ofselected transparent plastic, and depositing a layer of indium tin oxidewith a thickness of the fourth threshold (e.g. 200 nm) as a transparentbottom gate by RF magnetron sputtering, then, patterning the transparentbottom gate by de-photoresist, depositing a layer of aluminum oxide witha thickness of the fifth threshold (e.g. 50 nm) by atomic forcedeposition as the transparent gate insulating layer, the transparentgate insulating layer is patterned by ultraviolet lithography andphosphoric acid wet-etching technology.

After the preparation of the transparent gate insulating layer above thesubstrate made of the selected transparent plastic is completed,depositing a layer of indium tin oxide with a thickness of the sixththreshold (e.g. 500 nm) as a transparent source-drain by magnetronsputtering. After coating the photoresist and patterning the photoresistby UV lithography, exposing the indium tin oxide by wet-etching withphosphoric acid, the unexposed indium tin oxide is further de-photoed toprepare transparent source-drain patterns.

In step S202, the transparent source-drain of the selected substrate arerinsed with acetone, methanol and isopropanol and the cleanedsource-drain is dried with a nitrogen concentration of a certainconcentration (a concentration higher than 70%). Further, the cleanedsource-drain was subjected to ozone cleaning for 60 seconds underultraviolet light. Before the transparent active layer was formed, thetransparent source-drain after ozone cleaning was bombarded with oxygenplasma for 60 seconds. It should be noted that ozone cleaning and oxygenplasma treatment include oxygen plasma bath and injection. Oxygen plasmatreatment can clean the organic impurities on the surface of theconductive metal oxide at the source-drain and at the same time increasethe oxygen content at the surface of the transparent conductive metaloxide at the source-drain and enhance the surface polarization so as toregulate the work function of the surface of the transparent conductivemetal oxide.

The transparent active layer is made of a carbon material, whichincludes the semiconducting carbon nanotubes, the graphene and thesilicon carbide. The specific method for preparing the active layer isas follows:

(1) when the transparent active layer is prepared by using thesemiconducting carbon nanotubes or the silicon carbide, immersing thetransparent source-drain after the oxygen plasma bombardment into thesemiconducting carbon nanotube solution or the silicon carbide solution.So that a layer of thin film deposited thereon is taken out and baked ata certain temperature (for example, 150° C., for 30 minutes) to obtain acarbon nanotube network-like thin film or a silicon carbide network-likethin film, then coating the photoresist on the carbon nanotubenetwork-like thin film or the silicon carbide network-like thin film,and etching the remaining portions of the carbon nanotube network-likethin film or the silicon carbide network-like thin film except for thechannel portion of the transistor with oxygen ions, continuing to removethe carbon nanotube network-like thin film or silicon carbidenetwork-like thin film in the channel above the transistor part of thephotoresist, and preparing a carbon nanotube channel or a siliconcarbide channel film to obtain a transparent active layer prepared fromsemiconductor carbon nanotubes or silicon carbide;(2) when graphene is used to prepare the transparent active layer,transferring the graphene grown on the copper foil to a transparentsource-drain after oxygen plasma bombardment by polymethylmethacrylatetransfer technology to form a thin film, then applying photoresist overthe thin film formed of graphene and etching the rest of the thin filmformed by graphene with oxygen ions except for the channel portion ofthe transistor, continuing to remove the photoresist over the channelportion of the transistor in the thin film of graphene, and obtaining atransparent active layer prepared from graphene.

In step S203, above the transparent active layer made of one of thesemiconducting carbon nanotubes, silicon carbide and graphene, atransparent passivation layer is covered by a chemical vapor depositionmethod of a certain thickness (e.g. 500 nm) of silicon dioxide; thetransparent passivation layer is also made of the same transparentinsulating material as the transparent insulating gate layer.

As shown in FIG. 3, Embodiment 3 of the present disclosure provides amanufacturing method of a thin film transistor, which shows amanufacturing method of a non-fully transparent double-gate structurecarbon-based material thin film transistor. The method includes thefollowing steps:

step S301, selecting a substrate, and forming a bottom gate, a gateinsulating layer and a source-drain from bottom to top in sequence abovethe selected substrate, wherein the source-drain adopts a conductivemetal oxide with an adjustable work function as a metal conductingelectrode;step S302, rinsing and drying the source-drain of the selectedsubstrate, performing ozone cleaning to the dried source-drain for apredetermined time under a predetermined illumination condition, andbombarding the source-drain after the ozone cleaning with oxygen plasmafor a period of time, and further forming an active layer made of acarbon material over the source-drain after the oxygen plasmabombardment; andstep S303, sequentially forming a passivation layer and a top gate frombottom to top on the active layer, after the active layer is prepared.

Corresponding to the manufacturing method of a thin film transistor inEmbodiment 1 of the present disclosure, the manufacturing method of athin film transistor in Embodiment 2 of the present disclosure adds themanufacturing process of the top gate. The preparation process of thetop gate is the same as that of the bottom gate. For example, a layer ofindium tin oxide with a thickness of 100 nm is deposited as a top gateby RF magnetron sputtering. The preparation process of the substrate,the bottom gate, the gate insulating layer, the source-drain, the activelayer and the passivation layer of the manufacturing method of a thinfilm transistor of Embodiment 2 of the present disclosure is the same asthat of the substrate, the bottom gate, the gate insulating layer, thesource-drain, the active layer and the passivation layer of themanufacturing method of a thin film transistor of Embodiment 1 of thepresent disclosure. Therefore, for the preparation process of thespecific substrate, the bottom gate, the gate insulating layer, thesource-drain, the active layer and the passivation layer, reference maybe made to the related content in Embodiment 1 of the presentdisclosure, and details are not described herein again.

As shown in FIG. 4, a manufacturing method of a thin film transistoraccording to a fourth embodiment of the present disclosure is shown. Themethod shows a manufacturing method of a full-transparent double-gatestructure carbon-based material thin film transistor. The methodincludes the following steps: step S401, selecting a substrate made of atransparent material and forming a transparent bottom gate, atransparent gate insulating layer and a transparent source-drainsequentially from bottom to top over the selected substrate; thetransparent source-drain adopts a transparent conductive metal oxidewith an adjustable work function as a metal conducting electrode;

step S402, rinsing and drying the transparent source-drain of theselected substrate, and subjecting the dried transparent source-drain toa predetermined time of ozone cleaning under predetermined lightingconditions, then bombarding the transparent source-drain of the ozonecleaning with oxygen plasma for a period of time, further forming atransparent active layer made of a carbon material over the transparentsource-drain after the oxygen plasma bombardment;step S403, sequentially forming a transparent passivation layer and atransparent top gate on the transparent active layer from bottom to top,after the preparation of the transparent active layer is complete.

Wherein, the transparent top gate is made of a transparent conductivemetal oxide as a metal conducting electrode.

Corresponding to the manufacturing method of a thin film transistor ofEmbodiment 2 of the present disclosure, the manufacturing method of athin film transistor of Embodiment 4 of the present disclosure adds thepreparation process of the transparent top gate. The preparation processof the transparent top gate is the same as that of the transparentbottom gate. For example, a layer of indium tin oxide with a thicknessof the seventh threshold (e.g. 100 nm) is deposited as a transparent topgate by RF magnetron sputtering. The preparation process of thesubstrate, the transparent bottom gate, the transparent gate insulatinglayer, the transparent source-drain, the transparent active layer andthe transparent passivation layer of the manufacturing method of a thinfilm transistor of Embodiment 4 of the present disclosure is the same asthat of the substrate, the transparent bottom gate, the transparent gateinsulating layer, the transparent source-drain, the transparent activelayer and the transparent passivation layer of the manufacturing methodof a thin film transistor of Embodiment 2 of the present disclosure.Therefore, for the preparation process of the specific substrate, thetransparent bottom gate, the transparent gate insulating layer, thetransparent source-drain, the transparent active layer and thetransparent passivation layer, reference may be made to the relatedcontent in Embodiment 2 of the present disclosure, and details are notdescribed herein again.

As shown in FIG. 5, which is a manufacturing method of a thin filmtransistor according to Embodiment 5 of the present disclosure, themethod shows a manufacturing method of a non-fully transparent top gatestructure carbon-based material thin film transistor, and specificallyincludes the following steps: step S501, selecting a substrate, andforming a source-drain on the selected substrate; wherein thesource-drain adopts a conductive metal oxide with an adjustable workfunction as a metal conducting electrode;

step S502, rinsing and drying the source-drain of the selectedsubstrate, performing ozone cleaning to the dried source-drain for apredetermined time under a predetermined illumination condition, andbombarding the source-drain after the ozone cleaning with oxygen plasmafor a period of time, and further forming an active layer made of acarbon material over the source-drain after the oxygen plasmabombardment; andstep S503, sequentially forming a passivation layer and a top gate frombottom to top on the active layer, after the active layer is prepared.

Corresponding to the manufacturing method of a thin film transistor ofEmbodiment 3 of the present disclosure, the manufacturing method of athin film transistor of Embodiment 5 of the present disclosure omits thepreparation process of the bottom gate and the insulating gate layer.The preparation process of the active layer, the passivation layer andthe top gate in the manufacturing method of a thin film transistor ofEmbodiment 5 of the present disclosure corresponds to the active layer,the passivation layer and the top gate in the manufacturing method of athin film transistor of Embodiment 3 of the present disclosure.Therefore, for the preparation process of the specific active layer, thepassivation layer and the top gate, reference may be made to the relatedcontent in Embodiment 3 of the present disclosure, and details are notdescribed herein again.

However, in step S501, the source-drain is directly prepared on thesubstrate. Due to the different substrate materials, the source-drainprepared above are also prepared differently according to the followingmethod:

in one embodiment, a silicide (e.g. quartz, glass) substrate isselected, and depositing a conductive metal oxide or a transparentconductive metal oxide with an adjustable work function to a certainthickness (e.g. 100 nm) on the silicide substrate by using a radiofrequency magnetron sputtering method as a drain-source.

In another embodiment, a plastic substrate is selected, the selectedplastic substrate is placed in acetone and isopropanol, washed withnitrogen and then ultrasonically cleaned; a patterned photoresist isformed over the selected plastic substrate by UV lithography, and aradio frequency magnetron sputtering method is used for depositing aconductive metal oxide or a transparent conductive metal oxide with anadjustable work function to a certain thickness (e.g. 500 nm) as asource-drain. After coating the photoresist and patterning thephotoresist by UV lithography, exposing the indium tin oxide bywet-etching with phosphoric acid, the unexposed conductive metal oxideor the transparent conductive metal oxide is further de-photoresist toprepare source-drain patterns.

As shown in FIG. 6, which is a manufacturing method of a thin filmtransistor according to Embodiment 6 of the present disclosure, themethod shows a manufacturing method of a fully transparent top gatestructure carbon-based material thin film transistor, and specificallyincludes the following steps:

step S601, selecting a substrate, and forming a transparent source-drainover the selected substrate; wherein the transparent source-drain uses atransparent conducting metal oxide with an adjustable work function as ametal conducting electrode;

step S602, rinsing and drying the transparent source-drain of theselected substrate, and subjecting the dried transparent source-drain toa predetermined time of ozone cleaning under predetermined lightingconditions, then bombarding the transparent source-drain of the ozonecleaning with oxygen plasma for a period of time, further forming atransparent active layer made of a carbon material over the transparentsource-drain after the oxygen plasma bombardment;step S603, sequentially forming a transparent passivation layer and atransparent top gate on the transparent active layer from bottom to top,after the preparation of the transparent active layer is complete.

Corresponding to the manufacturing method of a thin film transistor ofEmbodiment 4 of the present disclosure, the manufacturing method of athin film transistor of Embodiment 6 of the present disclosure omits thepreparation process of the transparent bottom gate and the transparentinsulating gate layer. The manufacturing process of the substrate, thetransparent source-drain, the transparent active layer, the transparentpassivation layer and the transparent top gate in the manufacturingmethod of a thin film transistor of Embodiment 6 of the presentdisclosure is the same as that of the substrate, the transparentsource-drain, the transparent active layer, the transparent passivationlayer and the transparent top gate in the manufacturing method of thethin film transistor of Embodiment 4 of the present disclosure.Therefore, for the preparation process of the specific substrate, thetransparent source-drain, the transparent active layer, the transparentpassivation layer and the transparent top gate, reference may be made tothe related content in Embodiment 4 of the present disclosure, anddetails are not described herein again.

However, in step S601, the transparent source-drain are directlyprepared on the substrate. Due to the different substrate materials, thetransparent source-drain prepared above is also prepared differentlyaccording to different preparation methods as follows:

in one embodiment, when a substrate made of quartz or glass is selected,a selected layer of indium tin oxide with a thickness of the eighththreshold (e.g. 500 nm) is deposited on the substrate made of quartz orglass by radio frequency magnetron sputtering as a transparentsource-drain. Then, the transparent source-drain pattern is prepared bycoating a photoresist, exposing, etching, and removing photoresist.

In another embodiment, when a substrate made of transparent plasticmaterial is selected, a substrate made of the selected transparentplastic material is placed in acetone and isopropyl alcohol andultrasonically cleaned and then dried with nitrogen gas. A patternedphotoresist is formed by UV lithography over a substrate of selectedtransparent plastic, and a layer of indium tin oxide with a thickness ofthe ninth threshold (for example, 500 nm) is deposited as a transparentsource-drain by RF magnetron sputtering. After coating the photoresistand patterning the photoresist by UV lithography, exposing the indiumtin oxide by wet-etching with phosphoric acid, the unexposed indium tinoxide is further de-photoresist to prepare transparent source-drainpatterns.

Understandably, a layer of indium tin oxide with a thickness of thetenth threshold (e.g. 500 nm) is deposited as a transparent top gate byRF magnetron sputtering.

Corresponding to the manufacturing method of a thin film transistor ofEmbodiment 1 of the present disclosure, Embodiment 7 of the presentdisclosure provides a thin film transistor, which is prepared by themanufacturing method of a thin film transistor of Embodiment 1 of thepresent disclosure. The thin film transistor is a carbon-based materialthin film transistor with a non-fully-transparent bottom gate structure.

As shown in FIG. 7, corresponding to the manufacturing method of a thinfilm transistor of Embodiment 2 of the present disclosure, Embodiment 8of the present disclosure provides another thin film transistor, whichis prepared by the manufacturing method of a thin film transistor ofEmbodiment 2 of the present disclosure. The thin film transistor is afully transparent bottom gate structure carbon-based material thin filmtransistor. In FIG. 7, the substrate 11, the transparent bottom gate 12,the transparent gate insulating layer 13, the transparent source-drain14, the transparent active layer 15, and the transparent passivationlayer 16.

Corresponding to the manufacturing method of a thin film transistor ofEmbodiment 3 of the present disclosure. Embodiment 9 of the presentdisclosure provides yet another thin film transistor, which is preparedby the manufacturing method of a thin film transistor in Embodiment 3 ofthe present disclosure, which is a non-fully transparent double-gatestructure carbon-based material thin film transistor.

As shown in FIG. 8, corresponding to the manufacturing method of thethin film transistor of Embodiment 4 of the present disclosure,Embodiment 10 of the present disclosure provides yet another thin filmtransistor, which is prepared by the manufacturing method of a thin filmtransistor of Embodiment 4 of the present disclosure, the thin filmtransistor is a fully transparent double-gate structure carbon-basedmaterial thin film transistor. In FIG. 8, substrate 21, transparentbottom gate 22, transparent gate insulating layer 23, transparentsource-drain 24, transparent active layer 25, transparent passivationlayer 26, transparent top gate 27.

Corresponding to the manufacturing method of a thin film transistor ofEmbodiment 5 of the present disclosure. Embodiment 11 of the presentdisclosure provides still another thin film transistor, which isprepared by the manufacturing method of a thin film transistor inEmbodiment 5 of the present disclosure, which is a non-fully transparenttop gate structure carbon-based material thin film transistor.

As shown in FIG. 9, corresponding to the manufacturing method of a thinfilm transistor of Embodiment 6 of the present disclosure, a furtherthin film transistor is provided of Embodiment 12 of the presentdisclosure, which is prepared by the manufacturing method of a thin filmtransistor of Embodiment 6 of the present disclosure. The thin filmtransistor is a fully transparent top gate structure carbon-basedmaterial thin film transistor. In FIG. 9, substrate 31, transparentsource-drain 34, transparent active layer 35, transparent passivationlayer 36, transparent top gate 37.

In summary, the present disclosure increases the two steps of ozonecleaning and oxygen plasma treatment on the conductive layers (i.e. thesource-drain) of the metal oxide on the mature process and process ofthe existing amorphous silicon thin film transistor, improving thesurface work function of the conductive metal oxide to make good ohmiccontact with the active layer of the carbon material so as to improvethe performance of the carbon-based thin film transistor device.Moreover, the present disclosure can be applied to the preparation of anon-transparent carbon-based material thin film transistor and also tothe preparation of a fully transparent carbon-based material thin filmtransistor.

The foregoing disclosure is merely a preferred embodiment of the presentdisclosure, and certainly cannot be used to limit the scope of thepresent disclosure. Therefore, equivalent changes made according to theclaims of the present disclosure are still within the scope of thepresent disclosure.

What is claimed is:
 1. A manufacturing method of a thin film transistor,comprising: step S11, selecting a substrate, and forming a bottom gate,a gate insulating layer and a source-drain from bottom to top insequence above the selected substrate, wherein the source-drain adopts aconductive metal oxide with an adjustable work function as a metalconducting electrode; step S12, rinsing and drying the source-drain ofthe selected substrate, performing ozone cleaning to the driedsource-drain for a predetermined time under a predetermined illuminationcondition, and bombarding the source-drain after the ozone cleaning withoxygen plasma for a period of time, and further forming an active layermade of a carbon material over the source-drain after the oxygen plasmabombardment; and step S13, forming a passivation layer over the activelayer after the formation of the active layer is completed.
 2. Themethod according to claim 1, wherein the step S11 specificallycomprises: when a substrate made of a silicide is selected, depositing alayer of conductive metal oxide having a thickness of first threshold onthe substrate made of the selected silicide by radio frequency magnetronsputtering as the bottom gate, and using plasma enhanced chemical vapordeposition to deposit a layer of silicon dioxide having a thickness ofsecond threshold as the gate insulating layer; after the formation ofthe gate insulating layer above the substrate made of the selectedsilicide is completed, depositing a layer of the conductive metal oxidehaving a thickness of third threshold by magnetron sputtering as thesource-drain, then preparing a source-drain pattern by coatingphotoresist, exposing, etching and removing photoresist.
 3. The methodaccording to claim 2, wherein the step S12 specifically comprises:soaking and flushing the source-drain of the substrate made by theselected silicide with acetone, methanol and isopropanol; drying therinsed source-drain with a certain concentration of nitrogen; ozonecleaning the dried source-drain for 60 seconds under ultraviolet light;and bombarding the source-drain after the ozone cleaning by oxygenplasma for 60 seconds, before the active layer formed from semiconductorcarbon nanotubes or silicon carbide is formed into a film; soaking thesource-drain after the oxygen plasma bombardment into a semiconductorcarbon nanotube solution or the silicon carbide solution, so that alayer of thin film deposited thereon is taken out and baked at a certaintemperature to obtain a carbon nanotube network-like thin film or asilicon carbide network-like thin film; then coating the photoresist onthe carbon nanotube network-like thin film or the silicon carbidenetwork-like thin film, and etching remaining portions of the carbonnanotube network-like thin film or the silicon carbide network-like thinfilm except for a channel portion of a transistor with oxygen ions;continuing to remove the photoresist above the channel portion of thetransistor in the carbon nanotube network-like thin film or the siliconcarbide network-like thin film to prepare a carbon nanotube channel or asilicon carbide channel film, so that an active layer formed fromsemiconductor carbon nanotubes or silicon carbide is obtained.
 4. Themethod according to claim 3, wherein the step S13 specificallycomprises: covering a certain thickness of silicon dioxide over theactive layer made of semiconductor carbon nanotubes or silicon carbideby a chemical vapor deposition method as a passivation layer, after theformation of the active layer made of semiconductor carbon nanotubes orsilicon carbide is completed.
 5. The method according to claim 4,wherein the selected substrate is a transparent substrate made of quartzor glass, and a transparent bottom gate, a transparent gate insulatinglayer, a transparent source-drain, a transparent active layer and atransparent passivation layer are formed above the correspondingsubstrate; wherein the transparent gate insulating layer and thetransparent passivation layer are both made of a transparent insulatingmaterial consisting of silicon dioxide, graphene oxide, silicon nitride,aluminum oxide and an organic transparent insulating material; thetransparent bottom gate and the transparent source-drain are made of atransparent conductive metal oxide with an adjustable work function as ametal conducting electrode, and the transparent conductive metal oxideconsists of indium tin oxide, aluminum zinc oxide, tin oxide fluoride,gallium zinc oxide and zinc tin oxide; the transparent active layer ismade of semiconductor carbon nanotube or silicon carbide.
 6. The methodaccording to claim 5, wherein the method further comprises: depositing alayer of the transparent conductive metal oxide having a thickness ofseventh threshold as a transparent top gate by RF magnetron sputtering.7. A manufacturing method of a thin film transistor, comprising: stepS21, selecting a substrate, and forming a bottom gate, a gate insulatinglayer and a source-drain from bottom to top in sequence above theselected substrate, wherein the source-drain adopts a conductive metaloxide with an adjustable work function as a metal conducting electrode;step S22, rinsing and drying the source-drain of the selected substrate,performing ozone cleaning to the dried source-drain for a predeterminedtime under a predetermined illumination condition, and bombarding thesource-drain after the ozone cleaning with oxygen plasma for a period oftime, and further forming an active layer made of a carbon material overthe source-drain after the oxygen plasma bombardment; step S23, forminga passivation layer over the active layer after the formation of theactive layer is completed; wherein the step S21 specifically comprises:placing a substrate made of a selected plastic in acetone andisopropanol, ultrasonic cleaning and then drying with nitrogen, when thesubstrate made of the plastic is selected; forming a patternedphotoresist on the selected plastic substrate by UV lithography and aconductive metal oxide with a thickness of fourth threshold deposited asthe bottom gate by RF magnetron sputtering, patterning the bottom gateby de-photoresist, and then depositing a non-transparent insulatingmaterial with a thickness of fifth threshold as the gate insulatinglayer by atomic force deposition technique, and patterning the gateinsulating layer through ultraviolet lithography and phosphoric acidwet-etching technology; depositing a conductive metal oxide with athickness of sixth threshold as the source-drain by magnetronsputtering, after the formation of the gate insulating layer above thesubstrate made of the selected plastic is completed, wet-etching anexposing indium tin oxide with phosphoric acid, after the photoresist iscoated and the photoresist on the coating is patterned by UVlithography, and preparing a source-drain pattern by removing thephotoresist of the unexposed conductive metal oxide.
 8. The methodaccording to claim 7, wherein the step S22 specifically comprises:soaking and washing the source-drain of the substrate made of selectedplastic with acetone, methanol and isopropanol, and drying the washedsource-drain with a nitrogen gas of a certain concentration, and ozonecleaning the dried source-drain for 60 seconds under ultraviolet light,before the active layer formed from graphene is film-formed, bombardingthe source-drain after the ozone cleaning with oxygen plasma for 60seconds; transforming a graphene grown on a copper foil bypolymethylmethacrylate onto the source-drain after the oxygen plasmabombardment to form a thin film, then coating the photoresist on thethin film formed by graphene and etching remaining portions of the thinfilm formed by graphene except for a channel portion of a transistorwith oxygen ions, continuing to remove the photoresist above the channelportion of the transistor in the thin film formed by graphene, so thatan active layer formed from graphene was obtained.
 9. The methodaccording to claim 8, wherein the step S23 specifically comprises:covering a certain thickness of silicon dioxide by a chemical vapordeposition method on the active layer made of graphene as a passivationlayer, after the formation of the active layer made of graphene iscompleted.
 10. The method according to claim 9, wherein the selectedsubstrate is a transparent substrate made of transparent plastic, and atransparent bottom gate, a transparent gate insulating layer, atransparent source-drain, a transparent active layer and a transparentpassivation layer are formed above the corresponding substrate; wherein,the transparent gate insulating layer and the transparent passivationlayer are both made of a transparent insulating material consisting ofsilicon dioxide, graphene oxide, silicon nitride, aluminum oxide and anorganic transparent insulating material; the transparent bottom gate andthe transparent source-drain are made of a transparent conductive metaloxide with an adjustable work function as a metal conducting electrode,and the transparent conductive metal oxide consists of indium tin oxide,aluminum zinc oxide, tin oxide fluoride, gallium zinc oxide and zinc tinoxide; the transparent active layer is made of graphene.
 11. The methodaccording to claim 10, wherein the method further comprises: depositinga transparent conductive metal oxide with a thickness of sevenththreshold on the transparent passivation layer as a transparent top gateby RF magnetron sputtering.
 12. A manufacturing method of a thin filmtransistor, comprising: step S31, selecting a substrate, and forming asource-drain on the selected substrate; wherein the source-drain adoptsa conductive metal oxide with an adjustable work function as a metalconducting electrode; step S32, rinsing and drying the source-drain ofthe selected substrate, performing ozone cleaning to the driedsource-drain for a predetermined time under a predetermined illuminationcondition, and bombarding the source-drain after the ozone cleaning withoxygen plasma for a period of time, and further forming an active layermade of a carbon material over the source-drain after the oxygen plasmabombardment; and step 33, sequentially forming a passivation layer and atop gate from bottom to top on the active layer, after the active layeris formed.
 13. The method according to claim 12, wherein the step S31specifically comprises: when a substrate made of silicide is selected,depositing a layer of the conductive metal oxide having a thickness ofthird threshold on the substrate made of silicide by magnetronsputtering as the source-drain, then preparing a source-drain pattern bycoating photoresist, exposing, etching and removing photoresist.
 14. Themethod according to claim 13, wherein the step S32 specificallycomprises: soaking and flushing the source-drain of the substrate madeby the selected silicide with acetone, methanol and isopropanol, dryingthe rinsed source-drain with a certain concentration of nitrogen, ozonecleaning the dried source-drain for 60 seconds under ultraviolet light,bombarding the source-drain after the ozone cleaning by oxygen plasmafor 60 seconds, before the active layer formed from semiconductor carbonnanotubes or silicon carbide is formed into a film; soaking thesource-drain after the oxygen plasma bombardment into a semiconductorcarbon nanotube solution or the silicon carbide solution, so that alayer of thin film deposited thereon is taken out and baked at a certaintemperature to obtain a carbon nanotube network-like thin film or asilicon carbide network-like thin film, then coating the photoresist onthe carbon nanotube network-like thin film or the silicon carbidenetwork-like thin film, and etching remaining portions of the carbonnanotube network-like thin film or the silicon carbide network-like thinfilm except for a channel portion of a transistor with oxygen ions,continuing to remove the photoresist above the channel portion of thetransistor in the carbon nanotube network-like thin film or the siliconcarbide network-like thin film to prepare a carbon nanotube channel or asilicon carbide channel film, so that an active layer formed fromsemiconductor carbon nanotubes or silicon carbide is obtained.
 15. Themethod according to claim 14, wherein the step S33 specificallycomprises: after the formation of the active layer made of semiconductorcarbon nanotubes or silicon carbide is completed, covering a layer ofsilicon dioxide with a certain thickness over the active layer made ofsemiconductor carbon nanotubes or silicon carbide by a chemical vapordeposition method as a passivation layer, and using a radio frequencymagnetron sputtering method to deposit a conductive metal oxide with athickness of seventh threshold on the passivation layer as the top gate.16. The method according to claim 15, wherein the selected substrate isa transparent substrate made of quartz or glass, and a transparentsource-drain, a transparent active layer, a transparent passivationlayer and a transparent top gate are formed above the correspondingsubstrate; wherein the transparent passivation layer is made oftransparent insulating material, the transparent insulating materialconsists of silicon dioxide, graphene oxide, silicon nitride, aluminumoxide and organic transparent insulating material; the transparentsource-drain adopts a transparent conductive metal oxide with anadjustable work function as a metal conducting electrode; thetransparent active layer is made of semiconductor carbon nanotube orsilicon carbide; the transparent top gate adopts a transparentconducting metal oxide with adjustable or non-adjustable work functionas a metal conducting electrode; the transparent conductive metal oxideconsists of indium tin oxide, aluminum zinc oxide, tin oxide, galliumzinc oxide, and zinc tin oxide.
 17. The method according to claim 12,wherein the step S31 further comprises: when a substrate made of plasticis selected, depositing a layer of the conductive metal oxide having athickness of third threshold on the substrate made of plastic bymagnetron sputtering as the source-drain, then preparing a source-drainpattern by coating photoresist, exposing, etching and removingphotoresist.
 18. The method according to claim 17, wherein the step S32further comprises: soaking and washing the source-drain of the substratemade of selected plastic with acetone, methanol and isopropanol, anddrying the washed source-drain with a nitrogen gas of a certainconcentration, and ozone cleaning the dried source-drain for 60 secondsunder ultraviolet light, before the active layer formed from graphene isfilm-formed, bombarding the source-drain after the ozone cleaning withoxygen plasma for 60 seconds; transforming a graphene grown on a copperfoil by polymethylmethacrylate onto the source-drain after the oxygenplasma bombardment to form a thin film, then coating the photoresist onthe thin film formed by graphene and etching remaining portions of thethin film formed by graphene except for a channel portion of atransistor with oxygen ions, continuing to remove the photoresist abovethe channel portion of the transistor in the thin film formed bygraphene, so that an active layer formed from graphene was obtained. 19.The method according to claim 18, wherein the step S33 furthercomprises: after the formation of the active layer made of graphene iscompleted, covering a layer of silicon dioxide with a certain thicknesson the active layer made of graphene by a chemical vapor depositionmethod as a passivation layer, and using a radio frequency magnetronsputtering method to deposit a conductive metal oxide with a thicknessof seventh threshold on the passivation layer as a top gate.
 20. Themethod according to claim 19, wherein the selected substrate is atransparent substrate made of transparent plastic, and a transparentsource-drain, a transparent active layer, a transparent passivationlayer and a transparent top gate are formed above the correspondingsubstrate; the transparent passivation layer is made of transparentinsulating material, the transparent insulating material consists ofsilicon dioxide, graphene oxide, silicon nitride, aluminum oxide andorganic transparent insulating material; the transparent source-drainadopts a transparent conductive metal oxide with an adjustable workfunction as a metal conducting electrode; the transparent active layeris made of graphene; the transparent top gate adopts a transparentconducting metal oxide with adjustable or non-adjustable work functionas a metal conducting electrode; the transparent conductive metal oxideconsists of indium tin oxide, aluminum zinc oxide, tin oxide, galliumzinc oxide, and zinc tin oxide.